The objective of this proposal is to examine the mechanisms by which perinatal HI causes long-term neurological functional alterations by focusing on the glutamatergic and NOS systems. Cerebellar granule cell cultures and brain slices prepared from rat pups, which have experienced neonatal HI, will first be used to examine whether neonatal HI has similar long-term effects on glutamate receptor and the NO system as intrauterine HI has, using excitatory amino acid-stimulated cyclic guanosine monophosphate formation and phosphoinositide hydrolysis, and NOS activity as parameters. Time course studies of protein expression of NMDA receptor subunits, subtypes of the metabotropic glutamate receptor, as well as NOS isoforms will be performed after intrauterine and neonatal HI, using Western blot and immunocytochemical staining. Expression of mRNA coding for these proteins will also be examined, using Northern blot and reverse transcriptase-polymerase chain reaction. Post-treatment with NOS inhibitor will be used in the neonatal HI model to examine whether it is effective in both reducing HI-induced brain injury and reversing HI-induced alterations in the expression of NOS and glutamate receptors.